The objective of the program is to provide undergraduate students and research- oriented medical students from diverse, underrepresented backgrounds with a short- term, intensive biomedical laboratory research experience for 8-10 weeks during the summer at the University of Pennsylvania. The long-term aim of the program is to increase the pool of underrepresented students committed to careers in cardiovascular, pulmonary, and hematologic research. Training is provided by a core group of 51 trainers who have extensive experience as mentors to trainees at all levels and whose research interests relate to aspects of the heart, lung, and blood, as well as by a secondary group of more than 50 additional prospective mentors who conduct NHLBI sponsored research. Each trainee devotes approximately 90% of his or her time to hands-on laboratory research, experimental design, data interpretation, directed readings, lab meetings, and journal clubs. Trainees participate in a scientific seminar series presented by University of Pennsylvania faculty, receive supplemental training in academically relevant areas, including scientific presentation skills and the responsible conduct of research, and are provided with a variety of optional peer-networking and career-development activities and workshops. Trainees present their work in at least one formal setting at the end of the program and are encouraged to continue their association with the laboratory; undergraduates may return for a second summer research experience. This proposal seeks to integrate training that was formerly provided separately, via two different NHLBI grants: R25-HL084665 (formerly T35- HL007719) was originally established in 1991 for research-oriented medical students in the School of Medicine at the University of Pennsylvania, and T35-HL007789 was established in 1993 for undergraduates from a geographically and culturally diverse array of colleges and universities who come to the University of Pennsylvania for the summer. It is expected that the integration of these programs will build on existing strengths and result in an enriched trainee experience.